RoboteQ Dual Channel Digital Motor Controller AX2550, User Manual, Page: 42 / 186

General Operation
42 AX1500 Motor Controller User’s Manual Version 1.9b. June 1, 2007
User Selected Current Limit Settings
The AX1500 has current sensors at each of its two output stages. Every 16 ms, this current
is measured and a correction to the output power level is applied if higher than the user
preset value.
The current limit may be set using the supplied PC utility. Using the PC utility is it possible
to set the limit with a 0.25A granularity from 3.25A to 30A
During normal operation, current limiting is further enhanced by the techniques described
in the following sections.
Temperature-Based Current Limitation
The AX1500 features active current limitation that uses a combination of a user defined
preset value (discussed above) which in turn may be reduced automatically based on mea-
sured operating temperature. This capability ensures that the controller will be able to work
safely with practically all motor types and will adjust itself automatically for the various load
conditions.
When the measured temperature reaches 80oC, the controller’s maximum current limit
begins to drop to reach 0A at 100oC. Above 100oC, the controller’s power stage turns itself
off completely.
TABLE 3. Effect of Heatsink temperature on Max Amps Limit
Temperature Max Amps
Below 80 oC 30A
80 oC 30A
85 oC 20A
90 oC 15A
95 oC 5A
100 oC 0
Above 100 oC Both Power Stages OFF
Position Sensor
Gear box
Position Feedback
FIGURE 16. Motor with potentiometer assembly for Position operation